Loosely Coupled Transformer Circuit for High-Frequency Galvanic Isolation
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Solution Overview
Problem
Existing transformer circuits for connecting electrical equipment to electrical networks face limitations in achieving high conversion efficiency and galvanic isolation at reasonable dimensions, particularly when operating at frequencies higher than a kilohertz, due to technological and cost constraints.
Innovation Solution
A loosely coupled air-type transformer circuit with resonant coils and bidirectional converters, operating at frequencies up to ten kilohertz, provides efficient galvanic isolation and compactness while maintaining high transformation efficiency, allowing for the connection of both electrical load and source types to electrical networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional transformer circuit is used to connect electrical equipment to an electrical network, then galvanic isolation and voltage adaptation are achieved, but the transformer dimensions become unreasonably large and conversion efficiency decreases when operating at high frequencies
Solution Approach 1:
The patent changes the operating frequency parameter from traditional low frequencies (50/60 Hz) to high frequencies (kilohertz range). This parameter change enables the use of smaller magnetic cores and windings while maintaining galvanic isolation, thus reducing transformer dimensions without sacrificing isolation performance
Solution Approach 2:
The patent employs resonant oscillation at high frequencies to transfer energy between primary and secondary circuits. By utilizing resonant frequency matching between series resonant circuits on both sides of the transformer, efficient energy transfer is achieved at high frequencies with compact dimensions
2Productivity
If the transformer operating frequency is increased to improve conversion efficiency and compactness, then transformation efficiency and size are improved, but technological and cost limits are reached
Solution Approach 1:
The patent employs periodic switching of electronic components (transistors, diodes, capacitors) to generate high-frequency oscillations. This periodic action at controlled frequencies enables efficient transformation while using standard electronic components, avoiding excessive technological complexity and cost
Solution Approach 2:
The patent replaces traditional mechanical transformer designs with an electronic resonant circuit system. By using electronic switching devices and resonant capacitors instead of purely magnetic coupling mechanisms, the system achieves high-frequency operation with improved efficiency and manageable manufacturing requirements
3Volume of stationary object
If a transformer circuit operates at high frequency to achieve compact dimensions, then size is reduced, but conversion efficiency and galvanic isolation performance deteriorate
Solution Approach 1:
The patent utilizes resonant oscillation at the specific high frequency to maximize energy transfer efficiency. By tuning the resonant frequency of both primary and secondary circuits to match, minimal energy loss occurs during high-frequency transformation, maintaining high conversion efficiency despite compact dimensions
Solution Approach 2:
The patent optimizes multiple parameters simultaneously: operating frequency, capacitance values, inductance values, and switching timing. By carefully adjusting these parameters to work together at the resonant frequency, the system achieves both compact size and high conversion efficiency without energy loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient and compact transformer circuits that support high-frequency operations, ensuring good galvanic isolation and transformation efficiency, and allows for bidirectional energy transfer between electrical equipment and networks.
Implementation Method 1
a second coil L2 magnetically coupled to the first coil L1
Implementation Method 2
a first and a second capacitor C1, C2 respectively associated with the first and the second coil L1, L2 so as to form with the corresponding coil a resonant circuit at the frequency f0
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
The invention relates to a transformer-based electrical circuit (1) for connecting electrical equipment (2), such as a renewable energy generator or an energy storage system, to an electrical network (3). The circuit comprises a first voltage converter (10) connected to the equipment; a transformer (20) connected to the first converter; and a second voltage converter (20) connected to the transformer (2) and the electrical network (3). The transformer (20) is a weakly coupled transformer, the magnetic coupling between the first coil (L1) and the second coil (L2) being less than 0.7. The transformer (20) includes a first and a second capacitor (C1, C2) associated respectively with a first and a second coil (L1, L2) so as to form with said corresponding coil (L1, L2) a resonant circuit at the frequency f0. The invention also relates to an electrical installation.